Preparation of hydrocarbon substituted succinic acid anhydrides



States 3,030,387 PREPARATION OF HYDROCARBON SUBSTI- TUTED SUCCINIC ACID ANHYDRIDES George J. Benoit, Jr., San Anselmo, Caliii, assignor to California Research Corporation, San Francisco, Calif.,

a corporation of Delaware No Drawing. Filed Aug. 1, 1956, Ser. No. 601,351

9 Claims. (Cl. 260-3463) ing purposes.

Certain hydrocarbon substituted succinic anhydrides, namely, the alkenyl succinic anhydrides, may be prepared by the condensation of monoolefins and maleic anhydride. Although these alkenyl succinic anhydrides and their ester derivatives have been employed in some of the above-describedapplications, they are generally unsatisfactory due to their susceptibility to oxidation which results in either destruction and loss of the compound or its deterioration into undesirable products such as tars and coke at high temperatures. For these reasons, the saturated hydrocarbon substituted succinic acid anhydrides, more specifically, the alkyl succinic anhydrides and their ester derivatives, are clearly preferred since they are much more resistant to oxidation.

Up to the present, however, the production of saturated hydrocarbon substituted succinic anhydrides, such as the alkyl succinic anhydrides, has been subject to several serious disadvantages. The processes in general have been complicated and expensive to operate and the yields have not been satisfactory. One particular disadvantage characteristic of the processes proposed heretofore has been in the two-step procedure of first condensing a monoolefin with maleic anhydride and then subjecting the unsaturated alkenyl succinic anhydride product thus obtained to carefully controlled, mild hydrogenation just suificient to saturate the olefinically bonded carbon atoms. A further disadvantage in the previously suggested processes has been the need for monoolefinic hydrocarbons which are in general demand and therefore sometimes diificult as well as expensive to obtain.

It has now been found that superior alkyl succinic acid anhydrides and cycloalkyl succinic acid anhydrides can be conveniently prepared in enhanced yields by an improved new process which comprises reacting a member of the group consisting of alkanes and cycloalkanes of from 3 to 40 carbon atoms with maleic anhydride in the presence of a peroxide free radical initiator catalyst.

The process, according to the invention, is straightforward and economical in operation. Excellent yields of the desirable oxidation resistant alkyl succinic anhydrides are obtained. A particular advantage of the process lies in the fact that the alkyl succinic anhydrides are produced in a single-step reaction, thus avoiding the complications and expense of extra equipment and loss in yields due to extra handling encountered in previously proposed twostep procedures. A further, more distinct advantage of the process according to the invention, however, lies in the fact that it employs the more readily available alkanes and cycloalkanes rather than monoolefinic hydrocarbons.

The alkanes and cycloalkanes employed in the process according to the invention as previously mentioned contain from 3 to 40 carbon atoms. Suitable alkanes and cycloalkanes, which may also be referred to as paraffins and cycloparaflins, include propane, butane, 2,3-dimethyl butane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, nonane, dodecane, hexadecane or cetane, eicosane, propylcyclohexane, triacontane, and the like. Parafiin waxes are also suitable. For present purposes, branched chain alkanes and cycloalkanes, particularly those containing from 6 to 32 carbon atoms, are preferred since they provide superior yields of the desired alkyl and cycloalkyl succinic anhydrides. Illustrative examples of such preferred branched chain alkanes and cycloalkanes include 2,3-dimethylbutane, methylcyclopentane, methylcyclohexane, and ethylated waxes obtained by reacting parafiin waxes with ethylene in the presence of an alkyl halide catalyst as described in US. Patent No. 2,741,649, issued April 10, 1956, to Abbott and Brooke.

As mentioned, maleic anhydride is employed in the process of the invention. Examples of other acids or acid anhydrides which may be reacted with alkanes or cycloalkanes in accordance with the invention include citraconic acid, ethylmaleic acid, glutaconic acid, itaconic acid, methylitaconic acid, etc.

According to the process of the invention the alkanes or cycloalkanes are reacted with maleic anhydride in the presence of a peroxide free radical initiator catalyst. Heating may be employed to promote the reaction. However, an advantage of the present process lies in the fact that unusually high temperatures are unnecessary. Thus, loss in yields due to thermal splitting of the reactants and products is avoided. For present purposes reaction temperatures of from about 220 F. (104 C.) to about 400 F. (204 C.) are preferred. The best yields of alkyl and cycloalkyl succinic anhydrides are apparently obtained with reaction temperatures in the range from about 280 (138 C.) to about 350 F. (177 C.) and these temperatures are still more preferred accordingly.

The alkanes or cycloalkanes may be reacted with the maleic anhydride at any suitable pressure. Pressures sufficient to maintain the reactants in a liquid state can be used to facilitate handling and avoid loss of materials. For present purposes autogenous pressures developed in a closed system by the reactions are found to be very satisfactory.

The reaction according to the process of the invention may be carried out over any period of time necessary to desired completion. Ordinarily, reaction times of from about 10 to about 20 hours are sufiicient for batch-type operations. Either shorter or longer reaction times may be employed to complete the reaction to the desired degree depending on the reactants and reaction conditions.

A peroxide free radical initiator catalyst is employed in the process of the invention as previously mentioned. Such catalysts include benzoyl peroxide, acetyl peroxide, tertiarybutyl hydroperoxide, ditertiarybutyl peroxide, dibenzoyl peroxide or ditertiaryamyl peroxide. Organic peroxide free radical initiator catalysts of these types are particularly suitable. However, for present purposes, ditertiarybutyl peroxide is the preferred free radical initiator catalyst since it provides outstanding yields of alkyl and cycloalkyl succinic anhydrides.

The 'alkanes or cycloalkanes are reacted with the maleic anhydride in equimo lar proportions. Excess alkane or cycloalkane is ordinarily employed up to tenfold molar excess in order to insure as complete reaction as possible. Unreacted alkane or cycloalkane is readily separated from the reaction mixture and may be recovered and recycled to the process.

The following examples are offered in further illustration of. the invention. Unless otherwise specified, the proportions are given on a weight basis.

asses 7 EXAMPLE I In this example cetane was reacted with maleic anhydride to produce cetyl succinic acid anhydride. The following materials were charged to a pressure bomb and maintained at a temperature of 284 F. for 12 hours: Cetane, g 1000 (3.5 mol). Maleic anhydride, g 196 (2.0 mol). Di-tert-butyl-peroxide, g 50.

After the reaction period the bomb was emptied and found to contain 250 g. of solid product and 952 g. of liquid. The liquid was distilled, yielding 872 g. of un reacted cetane and 80 g. of bottoms product which was the desired material. This material was readily soluble in benzene and on analysis gave the following results:

Theory For Cetyl Found succinic Anhydride zo aaoi) Carbon, percent 7 5. 13 74. 4 Hydrogen, percent 11. 12 11. Oxygen, percent-.-" 13. 75 14. 6 Bromine N 0 3 0 Infrared analysis shows the presence of paraffin chains and cyclic anhydride structures.

EXAMPLE II The production of methylcyclopentyl succinic anhy- 4 EXAMPLE III This example illustrated the production of methylcyclohexyl succinic anhydride by the reaction of methylcyclohexane with maleic anhydride.

The charge to the bomb consisted of:

Methylcyclohexane, g 1000 Maleic anhydride, g 100 Di-tert-butylperoxide, g 20 The conditions were the same as in the previous experiment, that is, a temperature of 320 F. for 12 hours. On opening the bomb, 93 g. of solid and 920 g. of liquid product were found. The liquid on distillation yielded 74 g. of bottom product, which was found to be readily The following table lists experimental data obtained in i the preparation of alkyl and cycloalkyl succinic anhydride in accordance with the process of the invention.

Table REACTION OF MALEIC ANHYDRIDE WITH SATURATED HYDROGARBONS Parts by Weight Yield Hydrocarbon Initiator Solvent Temp., Adduct, F. Percent 2 Hydro- MA 1 Initiator Solvent carbon 2,3-dimethylbutane DTBP None. 100 23 5. 8 284 Octane. N n 100 10 572 6 Do- None (10 100 10 600 10 D0 BP ..d0..... 100 10 1.0 222 2 Do DTBP Benzene 100 5 0. 62 284 12 Do. 100 5 1. 25 284 19 Do 100 10 2.0 320 6 Do 100 19. 6 5. 0 284 12 Ethylated Wax 100 10 1. 0 320 20 Cyclopentane 100 5 1. 25 284 Low Methylcyclopentane 100 10 2. O 320 14 Do 100 10 2.0 320 37 Do. 100 10 2. 0 320 33 Gyclohexane 100 10 2. 0 320 Low Methylcyclohexane DTBPW. 100 10 2. 0 320 34 1 MA=rnaleic anhydride.

2 Based on maleic anhydride charged. 8 D'IBP=Di-tert-buty1peroxide.

4 BP=benzoyl peroxide.

5 TBHP=Tert-butyl hydroperoxldc.

Paralfin wax reacted with ethylene to yield branched chain liquid hydrocarbon of about 450 molecular weight.

dride by the reaction of methylcyclopentane with maleic anhydride was illustrated by this example.

The experiment was carried out as in the previous example charging the following materials to the bomb: Methylcyclopentane, g 1000 Maleic anhydride, g 100 Di-tert-butylperoxide, g 20 In this case, the temperature was maintained at 320 F. for 12 hours. As in the previous experiment, most of the liquid material in the bomb was unreacted hydrocarbon but on distillation yielded 69 g. of reaction product.

The above test data show the efiicacy of the reaction of alkanes and cycloalkanes with maleic anhydride in accordance with the process of this invention with representative alkanes and cycloalkanes containing from 6 to 32 carbon atoms. Better yields are obtained with branched chain hydrocarbons than with hydrocarbons containing no substituents. Ditertiarybutyl peroxide is shown to be outstanding as the catalyst in the above reaction.

I claim:

1. A process for preparing alkyl succinic acid anhydrides and cycloalkyl succinic acid anhydrides which comprises reacting a molar excess of a member of the group consisting of alkanes and cycloalkanes of from 6 to 32 carbon atoms with maleic anhydride in a closed system under autogenous pressure at a temperature from about 220 F. to about 400 F. and in the presence of ditertiary butyl peroxide free radical initiator catflyst.

2. A process for preparing cetyl succinic acid anhydride which comprises reacting a molar excess of cetane with maleic anhydride in a closed system under autogenous pressure at a'temperature from about 220 F. to about 400 F. and in the presence of ditertiaryhutyl peroxide catalyst.

3. A process for preparing methylcyclopentyl succinic acid anhydride which comprises reacting in a molar excess of methylcyclopentane with maleic anhydride in a closed system under autogenous pressure at a temperature from about 220 F. to about 400 F. and in the presence of ditertiarybutyl peroxide catalyst.

4. A process for preparing methylcyclohexyl succinic acid anhydride which comprises reacting a molar excess of methylcyclohexane with maleic anhydride in a closed system under autogenous pressure at a temperature from about 220 F. to about 400 F. in the presence of ditertiarybutyl peroxide catalyst.

5. A process for preparing a long chain alkyl succinic acid anhydride which comprises reacting a molar excess of a liquid branched chain ethylated parafl'ln wax having a molecular weight of about 450 with maleic anhydride in a closed system under autogenous pressure at a temperature from about 220 F. to about 400 F. in the presence of ditertiary butyl peroxide catalyst.

6. A process for the preparation of 2,3-dimethylbutylsuccinic anhydride which comprises reacting one mole of maleic anhydride with more than one mole of 2,3-dimethylbutane at a temperature of about 140 C. in a closed system under autogenous pressure with a catalytic amount of ditertiarybutyl peroxide.

7. A process for the preparation of alkyl hydrocarbon and cycloalkyl hydrocarbon substituted succinic acid anhydrocarbons at a temperature above 100 C. and in the presence of a catalytic amount of organic peroxide.

8. A process for the preparation of alkyl hydrocarbon and cycloalkyl hydrocarbon substituted succinic acid anhydrides which comprises reacting one mole of maleic anhydride with more than one mole of hydrocarbon selected from the group consisting of alkyl and cycloalkyl hydrocarbons of from 6 to 32 carbon atoms at a temperature above 100 C. and in the presence of a catalytic amount of organic peroxide.

9. A process for the preparation of alkyl hydrocarbon and cycloalkyl hydrocarbon substituted succinic acid anhydrides which comprises reacting one mole of maleic anhydride with more than one mole of hydrocarbon selected from the group consisting of alkyl and cycloalkyl hydrocarbons of from 6 to 32v carbon atoms at a temperature above 100 C. and in the presence of a catalytic amount of ditertiarybutyl peroxide.

References Cited in the file of this patent UNITED STATES PATENTS 2,121,183 Binapfl Jan. 21, 1938 2,426,224 Kharash Aug. 26, 1947 2,628,238 Patrick Feb. 10, 1953 2,692,270 Beavers Oct. 19, 1954 

1. A PROCESS FOR PREPARING ALKYL SUCCINIC ACID ANHYDRIDES AND CLCLOALKYL SUCCINIC ACID ANHDRIDES WHICH COMPRISES REACTING A MOLAR EXCESS OF A MEMBER OF THE GROUP CONSISTING OF ALKANES AND CYLOALKANES OF FROM 6 TO 32 CARBON ATOMS WITH MALEIC ANHYDRIDE IN A CLOSED SYSTEM UNDER AUTOGENOUS PRESSURE AT A TEMPERATURE FROM ABOUT 220*F. TO ABOUT 400*F. AND IN THE PRESENCE OF DITERTIARY BUTYL PEROXIDE FREE RADICAL INITIATOR CATALYST. 